Increase In Eicosapentaenoic Acid Content Research Articles

Overexpression of plastid lipid-associated protein in marine diatom enhances the xanthophyll synthesis and storage.

Plastoglobules, which are lipoprotein structures surrounded by a single hydrophobic phospholipid membrane, are subcellular organelles in plant chromoplasts and chloroplasts. They contain neutral lipids, tocopherols, quinones, chlorophyll metabolites, carotenoids and their derivatives. Proteomic studies indicated that plastoglobules are involved in carotenoid metabolism and storage. In this study, one of the plastid lipid-associated proteins (PAP), the major protein in plastoglobules, was selected and overexpressed in Phaeodactylum tricornutum. The diameter of the plastoglobules in mutants was decreased by a mean of 19.2% versus the wild-type, while the fucoxanthin level was increased by a mean of 51.2%. All mutants exhibited morphological differences from the wild-type, including a prominent increase in the transverse diameter. Moreover, the unsaturated fatty acid levels were increased in different mutants, including an 18.9-59.3% increase in eicosapentaenoic acid content. Transcriptomic analysis revealed that PAP expression and the morphological changes altered xanthophyll synthesis and storage, which affected the assembly of the fucoxanthin chlorophyll a/c-binding protein and expression of antenna proteins as well as reduced the non-photochemical quenching activity of diatom cells. Therefore, metabolic regulation at the suborganelle level can be achieved by modulating PAP expression. These findings provide a subcellular structural site and target for synthetic biology to modify pigment and lipid metabolism in microalgae chassis cells.

Anticolorectal cancer activity of the omega-3 polyunsaturated fatty acid eicosapentaenoic acid

BackgroundOral administration of the omega-3 fatty acid eicosapentaenoic acid (EPA), as the free fatty acid (FFA), leads to EPA incorporation into, and reduced growth of, experimental colorectal cancer liver metastases...

Isolation of enhanced eicosapentaenoic acid producing mutants of Nannochloropsis oculata ST‐6 using ethyl methane sulfonate induced mutagenesis techniques and their characterization at mRNA transcript level

SUMMARYEthyl methane sulfonate‐induced mutagenesis techniques were used to obtain cerulenin and erythromycin resistant mutant strains, which show a marked increase of 29 and 12%, respectively, in eicosapentaenoic acid content compared to the wild type (WT) strain. The increase in eicosapentaenoic acid content in both strains correlated well with a concomitant increase in 14:0, 16:0, 16:1, 18:0 and 20:4 n − 6 content of fatty acids. However, the linoleic acid content increased only in the cerulenin resistant strain, whereas the erythromycin resistant strain was completely devoid of this fatty acid, providing a contrasting feature for further study. Partial characterization of the mutant strains based on whole cell ultrastructure, growth patterns with or without selection pressure as well as at different temperatures revealed that the mutants were more thermotolerant, and maintained their morphological and genomic fidelity, although minor changes in band patterns were noted with random amplified polymorphic DNA techniques compared to the WT strain. Therefore, the developed new strains could have wider applications as planktonic feed for the mariculture industry. Further characterization of the mutants at the molecular level revealed that steady‐state mRNA transcript levels of chloroplast‐localized Δ12 desaturase and stearoyl‐ACP desaturase genes showed a contrasting transcript profile. However, the level of endoplasmic reticulum‐localized Δ12 desaturase mRNA transcript in either of the mutant strains was almost equal to that of the WT strain. Based on this observation, we postulate that the complete loss of 18:2 fatty acid content in the erythromycin resistant strain might be a result of mutation in the chloroplast‐localized Δ12 desaturase gene and that the increased content of very long chain‐polyunsaturated fatty acids might result from extrachloroplastic lipid desaturase activity, a phenomenon similar to that in the majority of angiosperms.

ＥＰＡ‐Ｅ投与によるラット白血球ＬＴＢ４産生の変化

To clarify the anti-inflammatory effect of eicosa-pentaenoic acid (EPA), we investigated the effect of EPA administration on A23187-stimulated LTB4 formation by rat leukocytes. LTB4 is known to be an important mediator of inflammation and the decreased formation of LTB4 is thought to be one of the important mechanism of anti-inflammatory effect of EPA. EPA ethyl ester (EPA-E) administration (100 mg, 300 mg and 1, 000 mg/kg/day) for 4 weeks dose dependently suppressed the formation of LTB4 and increase in the formation of LTB5 with the increase in EPA content in rat leukocytes. The content of docosapentaenoic acid (DPA) also dose-dependently increased and the content of arachidonic acid (AA) and docosahexaenoic acid (DHA) were decreased by the administration of 300 mg and 1000 mg of EPA-E daily. The formation of LTB4 in stimulated leukocytes and the content of AA are positively correlated.FMLP-induced chemotactic activity of leukocytes were suppressed with the EPA-E treatment but FMLP stimulated β-glucuronidase release was not affected by EPA administration.In conclusion, highly purified EPA-E administration reduced the formation of proinflammatory LTB4, increased the LTB5, which would competitively inhibit the action of LTB4 and suppressed the chemotactic activity of leukocytes, these might result in the suppression of inflammatory response.

エイコサペンタエン酸（ＥＰＡ）が赤血球変形能を改善する機序について

Eicosapentaenoic acid (EPA) is known by its anti-atherogenic and anti-thrombotic properties. This protective character of the fatty acid is usually explained through the shift of prostanoid production toward anti-thrombotic direction including depression of platelet aggregability. Since 1981 we have been reporting the effect of EPA on hemorheology. Because there is a possibility that viscosity of fatty acids themselves may be reflected in membrane fluidity, hence RBC filterability, we measured viscosities of triglycerides and ethylesters of EPA, and other fatty acids. It was found that triglycerides and ethylester of EPA are the less viscous oils than triglycerides and ethylesters containing other fatty acids measured in the experiment, respectively. It is important to prove directly that an increase in EPA content in RBC membrane could increase membrane fluidity.